Digi NS9750 - Manual (Page 734)

U S B d e v i c e b l o c k
7 1 0 N S 9 7 5 0 H a r d w a r e R e f e r e n c e
given pipe has not been configured or updated, or otherwise is not ready to send or
receive the required data, the device block issues
NAKs
to the USB.
The host block supports the Open Host Controller Interface (OHCI) interface model
for USB communications. The host block provides the registers and BBus mastering
capability to traverse transaction lists in system memory per the OHCI interface, as
well as transferring the in/out data to and from system memory.
USB device block
Figure 102 shows the architecture of the USB device block:
Figure 102: USB device block
Control and status
The control and status for the USB device block is provided through the slave
interface. The device block contains the registers used to program each of the 12
logical endpoints and the five configurations.
text
CSRs
D
E
V
D
M
A
Non-Ctrl
Endpoint
FIFO
FIFO
Ctrl In
Ctrl Out
SIE
M
U
X
XCVR
Slave
Master
BBUS
From
Host
To
Host
USB